This invention relates to the fabrication of metal articles from a plurality of members and, more particularly, to the fabrication of articles of non-uniform sectional or wall thickness from members including a plurality of sheet metal members.
The manufacture of complex, accurately shaped metal components, for example of the type used in such power producing apparatus as gas turbine engines, has included the steps of providing a forging, frequently of large size, and then machining the forging to provide in certain areas cross-sectional thicknesses approximating that of sheet metal. A typical example of such a structure is a complex titanium compressor casing of varying wall or cross-sectional thickness machined from a large forging. Such an approach has resulted in a material utilization factor of up to 8:1, for example an 800-pound forging is required to produce a 100-pound component.
Obviously, such current manufacturing procedures are costly from the standpoint of inefficient use of labor and of material.
It is a principal object of the present invention to provide an improved manufacturing method for the provision of an article including a portion of non-uniform sectional thickness employing the fabrication of a plurality of relatively simple, inexpensive members.
Another object is to provide such method which employs sheet metal members and the use of solid state diffusion bonding to join members into an article.
Still another object is to provide an improved fabricated article from a plurality of sheet metal and other members.
These and other objects and advantages will be more clearly understood from the following detailed description, the drawings and the examples, all of which are intended to be typical of rather than in any way limiting on the scope of the present invention.
Briefly, the method associated with the present invention for fabricating an article of non-uniform sectional thickness includes the steps of providing a plurality of cooperating sheet metal members or member portions (hereinafter referred to as members) and at least one insert comprising at least one insert member, the insert providing increased sectional thickness in at least one selected portion. Each of the members, including the insert member or members, is provided in a size and shape predetermined by the size and shape of the article and by the size and shape of other members so that together the members define the size and shape of the article. Each sheet metal member has a bonding surface which cooperates with a bonding surface of another member, typically another sheet metal member. Such members are assembled so that cooperating bonding surfaces face one another and so that the sheet metal members retain the insert between them. Thereafter, the sheet metal members are joined at cooperating bonding surfaces through solid state diffusion bonding. This provides an improved fabricated article of non-uniform sectional thickness and which can be considered to be a preform nearly to the shape desired in a finished article. Such a preform requires only a relatively small amount of additional work, such as machining in selected areas, to complete the manufacture.
The fabricated article of the present invention comprises a plurality of such sheet metal members and at least one such insert retained between the sheet metal members which are joined at bonding surfaces through a solid state diffusion joint.